Lab 4: Scale and Update Deployments

In this lab, you’ll learn how to update the number of instances a deployment has and how to modify the API backend.

For this lab, you need a running deployment of the k8sdemo application from the previous lab. If you deleted it, recreate it.

Scale apps with replicas

A replica is a copy of a pod that contains a running service. By having multiple replicas of a pod, you can ensure your deployment has the available resources to handle increasing load on your application.

  1. kubectl provides a scale subcommand to change the size of an existing deployment. Let’s increase our capacity from a single running instance of k8sdemo up to 10 instances:
 kubectl scale --replicas=4 deployment k8sdemo-backend -n default
 
 > deployment "k8sdemo" scaled

Kubernetes will now try to make reality match the desired state of 4 replicas by starting 2 new pods with the same configuration as the first.

  1. To verify that your changes have been rolled out, you can run:
 kubectl get pods -n default
 
 > NAME                              READY     STATUS    RESTARTS   AGE
  > k8sdemo-7d46f69d68-xcgcw          1/1       Running   0          19m
  > k8sdemo-backend-9c777544b-cp59q   1/1       Running   0          12m
  > k8sdemo-backend-9c777544b-jqjz9   1/1       Running   0          12m
  > k8sdemo-backend-9c777544b-lwssx   1/1       Running   0          12m
  > k8sdemo-backend-9c777544b-t5mlq   1/1       Running   0          12m

You should see output listing 4 replicas of your deployment.

**Congratulations!!! This concludes Lab 4 on scaling and updating Deployments **

Read more

Lab 3: Deploy your first application Lab 5: Stateful Deployments